Screen for granular materials



Feb. 7, 1933. Cl A SCOTT 1,896,595

SCREEN FOR GRANULAR MATERIALS Filed April 28 1926 2 Sheets-Sheet l A F d, i Fig. l.

f/ INVENTOR /f Quia adgxb ATTORN EY Feb. 7, 1933. c. A. SCOTT SCREEN FOR GRANULAR MATERIALS 2 Sheets-Sheet 2 v Filed April 28, 1926 lNvENToR Ze/4151, h 5M BY a,

ATTORNEY Patented Feb. 7, 1933 Leases' Vnr-irren srares PATENT "ori-lcs CHESTER A. SCOTT, or FORT WAYNE. INDiaNa-assieNOn To niais/run :OoNOnNiRA'rOi-*t COMPANY, OF roar WAYNE, iNnrANii, A CORPORATION or iNnIANA I SCIREIEIN FOB. Glti'-NUR MATERIALS Application filed April 2,8,

My invention relates to screens for granular materials and more particularly to means for sustaining the screen wire cloth'when under tension ready for use.

Heretofore very elicient screens have been constructed with a binding strip at each longitudinal end of the screening medium which is tree at the sides and is secured to the frame at the ends and vibrated by blows transmitted from above to a rigid cross meniber secured to the under side of the screening medium. TJhere the screening medium was bent sharply to attach it rigidly to the frame, particularly at the lower end, the

"'- constant vibration of the screen caused its longitudinal wires to crystallize and break.

The principal object ofmy invention is to provide a flexible connection at the longitudinal ends of the screening medium which is free at the sides, so that these suspension bar "'f' coming wave of the screening medium. This ensures vibration of the entire length ofv f-4ci'eeiiing medium, increasing the efficiency of the screen and practically eliminating the tendency of the longitudinal wires to crystal- E lize along the line where they are secured at the ends.

The particular embodiment of my invention selected for illustration is with my imf. provements added to a screen of the type shown in Letters Patent No. 1,456,067, issued to Richard A. Leahy May 22nd 1923.

Figure l is a top plan view of such a screening apparatus; i

F ig. Q is a side elevation of the same with parts of the supporting structure broken away, and a part of the side frame broken away at the delivery end to show the sustaining means;

Fig. 3, an enlarged detail, is of a portion of one side of the frame at the delivery, end, showing the means of iieXibly holding the screening medium in tension atthe delivery end by the knife blade support of the suspension bar;

ieee; serial No. ioaiii.

yend with simple, quickly.: adjusted tilting mechanism, consisting of a bar T with a gear-rack `t on one edge, whose teeth are adapted to be engagediby the teeth of the pinionzt1 liXed to the shaft 2 and adapted to be rotated-by the pilot wheel t3 to raise or lower theupper end of the screen frame. On its opposite edge the bar Tis provided with ratchet teethiit1 adapted to be engaged bythe pawl t5, so that theupper end of the screen will be heldin any' position to which it has been adjusted, until the pawl is thrown baclr out of engaging position with the ratchet teeth byineans or' the handle. 6. The in-` clination of the screen is adjusted from time tol timeas required to most elciently and vrapidly :screen ythe granular material fed upon-it. f

VThe' screenfraine F isffornied of any inaterial suitable for building a rigid structure capable of carrying the weight and bearing the strain, such asl-beams, lchannel irons, and 'angle bars bolted or'riveted together.

The iiexible` screening medium A may be of any desiredinesh ranging from that of veryline mesh to that which is very large. The screening-medium is linished at the upper longitudinal end by being clamped tightlyby bolts ae or otherwise between bars al, a2, faced with packing strips a3, a* respectivilely of rubber or other compressible materia. y

The suspension bar so formed has a `IJ- shaped Vstrap a5 toward each end pierced by Vthe shank of a bolt B whose cylindrical head Z2 rests in the U-strap in such a manner as to permit considerable freedom in upY and down vibration of the screen A. The bolt B passes through the upper end of the traine F and a bearing 'member Za? Whose horizontally placed knife edge bearing surface b3 bears upon the frame and is seated in a notch f1 in the frame member in such a manner as to add considerable additional freedom of vertical vibration to the screening medium when the nut b* is suitably tightened down.

At its lower or discharge end the screening medium is clamped tightly by bolts a7 or otherwise between a binding bar as and the suspension bar a faced with similar packing strips a3, a4 respectively.

The suspension bar a9 extends outwardly at each end beyond the edge of the screening medium to form a bearing am, having a knife edge bearing surface a adapted to oscillate in a V-shaped seat f3 in a bearing block f2 secured to the channel iron forming the side of the frame F by bolts f4 or in any other suitable manner, thus providing for an up and down rocking motion of the screen at the discharge end. This iexible suspension of the screening medium allows it to vibrate throughout its length.

A bridge member D supports the vibration mechanism d operated by motor d1 or otherwise and acting upon the screening medium through the tappet rod (L12.

It will be noted that this invention provides a screening apparatus of greatly improved screening eficiency. The screening medium is tensioned in an endwise direction and at each anchorage there is a knife edge pivot so constructed that the screening medium may vibrate freely between its points of suspension. The upper pivots are positioned beyond the upper end of the screening medium so that the pivot point at this end is beyond the end of the screen and accordingly there will be no dead point at that end but the screen will have a vibratory motion clear to the top. The lower end of the screen cloth passes over the edge of a bar which has its pivots laterally beyond the side edges of the screen. Accordingly, as the screen cloth is caused to vibrate at its medial portion, the waves of motion may travel clear to the lower end thereof. This means that there will be no blind or dead points anywhere on the screen and that even at thel lower end thereof, the material will be kept in agitation until it passes off the end of the screen. Placing the pivot points laterally outside of the edges of the screen cloth renders this end of the screen entirely free of obstruction.

Obviously many changes may be made in the apparatus without departing from the spirit of my invention and I claim as within the scope of my invention all forms readable on the claim.

I claim as my invention and desire to secure by Letters Patent of the United States In combination with an apparatus for screening granular material, having an inclined frame and a strip of resilient screening medium maintained under tension from the top and bottom edges in said frame, binding means for the bottom tension edge of said medium, a part of said binding means extended beyond the edge of said medium and provided with a knife-edge bearing adapted to co-act with said frame to form a flexible connection therewith, so that said vibration affect said end as well as the main body of the surface of said screening medium and permit the binding means to adjust itself to meet oncoming transverse waves of the screening medium, said connections being to the side of the frame at the delivery end, and said bottom edge binding means being free of other connections to the frame.

In testimony whereof I have hereunto set my hand.

CHESTER A. SCOTT. 

